The present invention relates to a valve operating device for an internal combustion engine, and, specifically, to a valve operating device wherein a camshaft having a plurality of cams of different profiles for operating an intake or an exhaust valve associated with an engine cylinder is operatively coupled to a timing wheel driveable by the crankshaft of the engine, and a selective coupling mechanism is disposed between a plurality of cam followers operable in response to rotation of the camshaft for selectively connecting the cam followers to control the operating mode of the intake or exhaust valve according to operating conditions of the engine.
One conventional valve operating device of the type described is known from Japanese Laid-Open Patent Publication No. 61-19911, for example. In such conventional valve operating device, the cam followers are selectively connected for operation by the respective cams for opening and closing the intake or exhaust valves, and thus control the lift of the respective intake or exhaust valves, that corresponds to the amount by which the cam lobe of each cam projects, and also control the opening interval of the intake or exhaust valve dependent on the angular interval of the cam lobe on each cam. To increase the accuracy of control of valve operation in internal combustion engines by such conventional devices the cam profiles are required to be greatly different from each other. In meeting this requirement, however, the selective coupling mechanism is subjected to great limitations and difficulty arises because of the number of cams required to be used and the large amount of space required to accommodate this number of cams.